EN
We establish Vallée Poussin type disconjugacy and disfocality criteria for the half-linear second order differential equation
$u'' = p(t)|u|^α |u'|^{1-α} sgn u + g(t)u'$,
where α ∈ (0,1] and the functions $p,g ∈ L_{loc}(a,b)$ are allowed to have singularities at the end points t = a, t = b of the interval under consideration.